In the use of optical signals to convey information in telecommunications networks, there are several optical signal processing functions that are typically performed at various points in a network, such as signal amplification, multiplexing/demultiplexing, filtering and switching.
In known optical communications systems, functions such as the aforementioned, are typically performed by specialized hardware arrangements comprised of often large numbers of discrete optical components. In complex systems, large collections of such arrangements can become physically quite large. Furthermore, such systems are subject to substantial signal losses due to long runs of fiber to interconnect the discrete components and due to losses at each of a large number of component interconnections. Other problems include fragility, greater susceptibility to environmental conditions, a greater effort and cost to assemble and difficulty in testing.
Moreover, due to the specialized nature of each circuit comprised of discrete components, modification of such circuits and the replacement of failed individual components is often difficult.